Comments on: LED POV hard drive clock

By: Cobra_Phil

Cobra_Phil — Tue, 13 Sep 2011 17:28:32 +0000

There is a project at kickstarter about a POV hard drive clock…
http://www.kickstarter.com/projects/680714141/hard-drive-ticktock-pov-clock

By: Sparky

Sparky — Mon, 20 Oct 2008 11:39:12 +0000

@Melvin: that was exactly what I thought, but you still need an index signal, because you not only need to know the speed but also the position of the disc.

Balancing the disc after cutting the slot shouldn’t be all that hard, just hang it on a smooth rod, spin it, and if it stops repeatedly in the same position, or rocks back and forth just before it stops, remove some material on the bottom side, and try again. This is basically how many mechanics still balance motorcycle wheels.

By: jesh

jesh — Mon, 20 Oct 2008 07:55:04 +0000

What about some PCB etching solution, or a related chemical etch to remove the stripe. A little contact paper to mask the area around it..

Or failing that, make one edge straight on top, make the other edge of your ‘slot’ straight on the bottom. The light shining through doesn’t care if there is a ragged edge opposing the straight one on the top or the bottom, as the magnetic material on the other side of the platter would mask it.
That would make it easier to just lay a straight edge on the platter and clean some of the material away with an x-acto or the like, then flip, repeat.

By: me

me — Sun, 19 Oct 2008 09:56:45 +0000

@david
I know it may be impractical, but you could put tape over the entire platter except the aria you wanted stripped and sand-blast it.

By: David

David — Sat, 18 Oct 2008 20:14:58 +0000

I wish I could bump this, but I wanted to say that Jaded is absolutely right about platters, especially smaller capacity ones being made of glass with a magnetic coating on top.

I’ve played around with the attachments I have for my dremel, but I’m hard-pressed to find something that can scrape off a clean line. Any ideas?

By: watch

watch — Sat, 18 Oct 2008 19:32:12 +0000

amazing !!! hats off to ur thinking.. i m sure u’ll come soon with more updates on this

By: meznak

meznak — Sat, 18 Oct 2008 18:46:33 +0000

@p3ngwin

i’m pretty sure i heard him say ’90 times a second’, which would be correct for a 5400 rpm drive.

By: Marvin

Marvin — Sat, 18 Oct 2008 18:21:50 +0000

You have to find hdds with a low capacity, the higher the capacity the higher the chance to get glass platters.

But with glass platters you have the chance to make the slit without changing the balance. (Maybe etching would be a possibility…)

As for the sync signal, you probably can use the tachometer signal from the drives motor.

By: ttt

ttt — Sat, 18 Oct 2008 17:25:32 +0000

great post

By: Wwhat

Wwhat — Sat, 18 Oct 2008 17:22:27 +0000

Pretty nicely done, but as he says himself you do want to put it in some soundmuffling enclosure, I’d go for glass I think, not sure acrylic will block much, plus it’s sensitive to scratches.

As for the clock ‘running backwards’ that would probably be an optical illusion caused by the refresh frequency of the camera I imagine.

By: p3ngwin

p3ngwin — Sat, 18 Oct 2008 07:38:46 +0000

5400 RPM
“spins that many times a second”

RPM means per MINUTE.

By: jaffamuffin

jaffamuffin — Sat, 18 Oct 2008 04:38:14 +0000

Why was the second hand on the clock moving in the wrong direction? Was it a backwards clock. Nevertheless, this is an awesome hack.

By: jaded

jaded — Sat, 18 Oct 2008 04:35:18 +0000

@davi,

Many hard drive platters made in the last 10 years or so are glass, not aluminum. Glass is a more stable material than aluminum.

All you need for the “slit” on a glass platter is to remove a stripe of the magnetic coating, which you could probably do with a carbide tipped scraper and a straightedge. You’d have to scrape both top and bottom of the platter, of course.

This is an awesome project, and I’m seriously thinking of making one. God knows I have enough crappy old hard drives!

By: nubie

nubie — Sat, 18 Oct 2008 00:34:54 +0000

Reezy, that would be awesome, have 2 or three of these doing visualizations, better yet mount it as part of a projector lens (like some auxiliary car lamps), then it would be a really neat graphic display for music.

By: nubie

nubie — Sat, 18 Oct 2008 00:33:11 +0000

That is awesome.

And that 2.5″ platter is glass? At least that is what I hear.

Try a 1.8″ HDD next :P, or go the other way and make a huge one out of something different, like maybe a car wheel with a full hubcap, and a line cut out of it :). Or a CD painted black maybe.